Glutathione is a peptide consisting of three amino acids, i.e., L-cysteine, L-glutamic acid, and glycine. Glutathione is present in a wide variety of living organisms including not only humans but also other animals, plants, and microorganisms, and it is an important compound for living organisms that is involved in, for example, removal of active oxygen species, detoxification, and amino acid metabolism.
Glutathione is present in vivo in the form of either reduced glutathione (N—(N-γ-L-glutamyl-L-cysteinyl)glycine) in which the thiol group of the L-cysteine residue is reduced in the form of SH (hereafter, it may be referred to as “GSH”) or oxidized glutathione in which the thiol group of the L-cysteine residue is oxidized to form a disulfide bond between two glutathione molecules (hereafter, it may be referred to as “GSSG”).
GSSG is known to be useful in the field of, for example, fertilizers, pharmaceuticals, and cosmetic products.
Patent Document 1 discloses a technique involving the use of a GSSG-containing medium to promote the rooting of plant seedlings. Patent Document 1 also discloses that nitrogen, phosphorus, and potassium are further added to a GSSG-containing medium. Patent Document 1 further discloses that a GSSG solution is spray-applied to leaves of plant seedlings.
Patent Document 2 discloses that GSSG is useful as an active component of a plant growth regulator that increases the harvest index. For example, it has activity of increasing the number of seeds and the number of flowers of the plant or increasing the number of lateral shoots or tillers of a plant. Patent Document 2 also discloses that GSSG is sprayed to a plant's leaf surface for plant growth promotion.